title: Metabolic engineering of Escherichia coli for biosynthesis of D-galactonate.
abstract: D-galactose is an attractive substrate for bioconversion. Herein, Escherichia coli was metabolically engineered to convert D-galactose into D-galactonate, a valuable compound in the polymer and cosmetic industries. D-galactonate productions by engineered E. coli strains were observed in shake flask cultivations containing 2 g L(-1) D-galactose. Engineered E. coli expressing gld coding for galactose dehydrogenase from Pseudomonas syringae was able to produce 0.17 g L(-1) D-galactonate. Inherent metabolic pathways for assimilating both D-galactose and D-galactonate were blocked to enhance the production of D-galactonate. This approach finally led to a 7.3-fold increase with D-galactonate concentration of 1.24 g L(-1) and yield of 62.0 %. Batch fermentation in 20 g L(-1) D-galactose of E. coli ∆galK∆dgoK mutant expressing the gld resulted in 17.6 g L(-1) of D-galactonate accumulation and highest yield of 88.1 %. Metabolic engineering strategy developed in this study could be useful for industrial production of D-galactonate.
authors.affiliation: Department of Energy and Biotechnology, Energy and Environment Fusion Technology Center (E2FTC), Myongji University, 116 Myongji-ro, Cheoin-gu, Yongin-si, Gyeonggi-do, 449-728, Republic of Korea.
authors.forename: Huaiwei
authors.initials: H
authors.lastname: Liu
authors.forename: Kristine Rose M
authors.initials: KR
authors.lastname: Ramos
authors.forename: Kris Niño G
authors.initials: KN
authors.lastname: Valdehuesa
authors.forename: Grace M
authors.initials: GM
authors.lastname: Nisola
authors.forename: Lenny B
authors.initials: LB
authors.lastname: Malihan
authors.forename: Won-Keun
authors.initials: WK
authors.lastname: Lee
authors.forename: Si Jae
authors.initials: SJ
authors.lastname: Park
authors.forename: Wook-Jin
authors.initials: WJ
authors.lastname: Chung
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D003470:Culture Media; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005691:Galactose Dehydrogenases / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D044224:Pseudomonas syringae / Q000201:enzymology; D013400:Sugar Acids / Q000737:chemistry / Q000378:metabolism*
chemical_list: D003470:Culture Media; D017931:DNA Primers; D013400:Sugar Acids; C012991:galactonic acid; D005691:Galactose Dehydrogenases; C047959:galactose dehydrogenase